1. Field of the Invention
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, etc. and a method of forming an image on a recording medium.
2. Discussion of the Background
Image forming apparatuses that form images on both sides of a recording medium such as a transfer sheet by a so-called switchback method are known.
In the switchback method, a visual image such as a toner image that has been formed on an image bearing member is transferred onto one side of a recording medium by a transfer device and is then fixed onto the one side of the recording medium by a fixing device. The recording medium is then reversed by a reversing path, etc., and is conveyed again to the transfer device and the fixing device so that another visual image that has been formed on the image bearing member is transferred and fixed onto the other side of the recording medium.
In the above image forming apparatuses using the switchback method, because a switchback mechanism for reversing a recording medium to be conveyed again to the transfer device and the fixing device is necessary, the cost of the image forming apparatus may be increased. Further, it may be difficult to perform a high speed image formation on both sides of a recording medium due to the switchback process. Moreover, a sheet jam may tend to occur at a time of the switchback process because a recording medium may tend to be curled when an image is fixed onto one side of the recording medium by heat.
FIG. 20 illustrates a schematic view of a background image forming apparatus in which visual images, which have been transferred onto both sides of a recording medium from a first image bearing member and a second image bearing member, are fixed at the same time. Specifically, the image forming apparatus transfers a first visual image formed on a photoreceptor 301 serving as a first image bearing member onto a transfer belt 302 serving as a second image bearing member by a first transfer device 303 and then transfers a second visual image formed on the photoreceptor 301 onto one side of a transfer sheet 304 by the first transfer device 303. Thereafter, the image forming apparatus transfers the first visual image on the transfer belt 302 onto the other side of the transfer sheet 304 by a second transfer device 305, thus transferring the visual images onto both sides of the transfer sheet 304. The transfer sheet 304 is then conveyed to a fixing device 306, where the visual images are fixed onto both sides of the transfer sheet 304 at the same time.
In the background image forming apparatus of FIG. 20, because the above-described switchback mechanism and process are not necessary, an increase of the cost of the apparatus and occurrence of sheet jam in a switchback process may be prevented. Further, a high speed image formation on both sides of a recording medium may be performed.
However, in the background image forming apparatus of FIG. 20, a transfer nip part formed between the photoreceptor 301 and the transfer belt 302 is relatively small. In other words, the photoreceptor 301 contacts the transfer belt 302 in a point contact state. In such a point contact state, stable transferring of an image may be difficult to achieve. Unstable transferring of an image may result in an inferior transfer of an image, and may result in image blurring.
According to one aspect of the present invention, an image forming apparatus includes an image bearing member configured to bear visual images, a visual image forming device configured to form the visual images on the image bearing member, and a two-side transfer device including a recording medium holding member spanning a plurality of stretch members to hold a recording medium thereon. The two-side transfer device is configured to transfer respective of the visual images on the image bearing member onto respective of both sides of the recording medium on the recording medium holding member while the recording medium holding member is moved in a predetermined direction. The image forming apparatus further includes a fixing device configured to fix the visual images transferred onto the both sides of the recording medium. The image bearing member intrudes into a part of the recording medium holding member spanning two adjacent stretch members of the plurality of stretch members by an intrusion amount of about 0.2 mm or greater so that the recording medium holding member moves in contact with the image bearing member, having a contact width in a predetermined direction.
Objects, features, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.